KR20180092847A - Iron-based composition for fuel element - Google Patents

Abstract

Disclosed embodiments include fuel assemblies, a fuel element, a cladding material, methods of making a fuel element, and methods of using the fuel element.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an iron-

Cross-reference to related application

This application is a continuation-in-part of application Serial No. 15 / 076,475, filed March 21, 2016. U.S. Application Serial No. 15 / 076,475 is a continuation-in-part of U.S. Application No. 13 / 794,589, filed March 11, 2013, which claims priority to U.S. Provisional Patent Application No. 61 / 747,054, filed December 28, , The entire contents of which are incorporated herein by reference.

Technical field

This patent application relates to a fuel element comprising a cladding material and a method for the fuel element.

The disclosed embodiments include fuel elements, fuel assemblies, cladding materials, and methods of making and using them.

The foregoing is therefore intended to be illustrative and not in a limiting sense, as such may involve a simplification, generalization, inclusion and / or omission of details, and consequently, those skilled in the art will recognize that the foregoing general description is merely exemplary in nature and is in no way intended to be limiting in any way. I will understand. In addition to any of the exemplary aspects, embodiments, and features described above, additional aspects, embodiments, and features will become apparent with reference to the drawings and the following detailed description. Other aspects, features, and advantages of the devices and / or processes and / or other subject matter described herein will be apparent in the teaching that is set forth herein.

Skilled artisans will appreciate that the drawings are for illustrative purposes primarily and are not intended to limit the scope of the novel subject matter described herein. The drawings are not necessarily to scale, and in some instances, various aspects of the novel subject matter disclosed herein may be exaggerated or enlarged in the drawings to facilitate an understanding of the various features. In the drawings, the same reference numerals generally refer to the same features (e.g., functionally similar elements and / or structurally similar elements).
BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B show, in an exemplary embodiment, a schematic cutaway perspective view of an exemplary nuclear fuel assembly and (b) an exemplary fuel element in (a) an exemplary embodiment.
Figures 2a and 2b-2f each provide a flow diagram of a process for making a composition and provide exemplary details of the process in an exemplary embodiment.
Figures 3A-3C show optical micrographs illustrating various microstructures of an iron-based composition through various processes in an exemplary embodiment.
Figures 4A and 4B-4E each provide a flow diagram for the process of making a composition and provide exemplary details of the process in another exemplary embodiment.
Figures 5A and 5B each provide a flow diagram for a process using a composition and provide exemplary details of the process in an exemplary embodiment.
Figures 6a and 6b show a process outline of the major process steps used to facilitate plate production and tube production in the heat (CH and DH).
FIG. 7 illustrates a typical transmission electron microscope (TEM) image illustrating a depth effect on a void generated by irradiation.
Figure 8 shows the swelling results for heat, illustrating the void swelling performance of the composition examples for ACO-3 achieved.
Figure 9 shows the TEM collage for the void microstructure at 4 hits after irradiation at 480 degrees Celsius to 0.28 mPa He / dpa up to 188 dpa, where the voids are shown as black pockets.
Figure 10 shows the TEM collage for the void microstructure in 4 heat after irradiation at 460 degrees Celsius to 0.015 apps He / dpa to 188 dpa.

Introduction

In the following detailed description, reference is made to the accompanying drawings which form a part of the detailed description. In the drawings, the use of similar symbols or similar symbols in the various figures generally indicates similar or identical articles, unless the context clearly indicates otherwise.

The illustrative embodiments, drawings, and claims set forth in the description are not intended to be limiting. Other embodiments may be utilized and other modifications may be made without departing from the spirit or scope of the subject matter presented herein.

Those skilled in the art will appreciate that the components (e.g., operations), devices, objects, and accompanying descriptions described herein are used as examples for conceptual clarity, and that various structural changes are contemplated. Consequently, when used herein, the specific examples described and the accompanying discussion are intended to represent each more general class. In general, the use of any specific example is intended to be representative of the group in question, and should not be construed as limiting the inclusion of a particular component (e.g., workpiece), device, and object.

This application uses explicit summary headings for clear presentation. It should be understood, however, that the abstract title is for illustrative purposes and that various types of subject matter may be discussed throughout the application (e.g., device (s) / structure (s) (S) / work may be described under the structure (s) / process (s) headings and / or the description of a single topic may span more than one topic heading. Thus, the use of formal abstract headings is not intended to be limiting in any way.

survey

In one aspect, a method of making a composition is presented, which comprises heating a material comprising an iron-based composition to a first temperature under a first condition in which at least a portion of the iron-based composition is transformed into an austenite phase, ; Cooling the material to a second temperature at a predetermined cooling rate under a second condition in which at least a portion of the iron-based composition is transformed into a martensite phase; And subjecting the material to a third temperature under a third condition in which the carbide precipitates.

In another embodiment, a method of making a composition is disclosed, the method comprising: passing the material through at least one of cold drawing, cold rolling, and pilgering; Subjecting the material containing the iron-based composition to a first temperature under a first condition in which at least a part of the iron-based composition is transformed into an austenite phase; Cooling the material to a second temperature at a predetermined cooling rate under a second condition in which at least a portion of the iron-based composition is transformed into a martensite phase; And subjecting the material to a third temperature under a third condition in which the carbide precipitates.

In another embodiment, a composition comprising (Fe) a (Cr) b (M) c is presented wherein a, b, and c are each greater than 0 representing weight percent and M is at least one B is between 11 and 12, c is between about 0.25 and about 0.9, a is the balance, and the composition comprises at least about 0.01 wt.% To about 0.04 wt.

In another embodiment, a composition comprising (Fe) a (Cr) b (Mo, Ni, Mn, W, V) c is presented wherein a, b and c are each greater than 0, B is between 11 and 12, c is between about 0.25 and about 0.9, a is the balance, at least substantially all of the composition represents a martensitic phase and the composition comprises from about 0.01% to about 0.04% ≪ / RTI >

In another embodiment, a method of using a fuel assembly is disclosed, the method comprising generating power using a fuel assembly, wherein the fuel element of the fuel assembly has a chemical composition (Fe) a (Cr) b (M) c Wherein a, b, and c are each a number greater than 0 representing weight percent, M is at least one transition metal element, b is between 11 and 12, and c is between about 0.25 About 0.9, a is the balance, and the composition comprises at least about 0.01% to about 0.04% N by weight.

In another embodiment, a fuel element is disclosed that comprises a tubular composition made by a method, the method comprising: providing an iron-based composition at a first temperature under a first condition in which at least a portion of the iron- Heat treating the containing material; Cooling the material to a second temperature at a predetermined cooling rate under a second condition in which at least a portion of the iron-based composition is transformed into a martensite phase; And subjecting the material to a third temperature under a third condition in which the carbide precipitates. In one embodiment, for compositions where nitrogen is present, precipitation of the carbide may involve precipitation of nitrides and carbonitrides.

Fuel assembly

IA shows a partial illustration of a nuclear fuel assembly 10 according to one embodiment. The fuel assembly may be a nuclear fissionable nuclear fuel assembly or a nuclear fuel assembly that is a source of nuclear fuel. The assembly may include a fuel element (i.e., a "fuel rod" or "fuel pin") 11. 1B shows a partial illustration of a fuel element 11 according to one embodiment. As shown in this embodiment, the fuel element 11 may include a cladding material 13, fuel 14, and in some cases at least one gap 15.

The fuel can be sealed in the cavity by means of the outer cladding material 13. In some cases, a plurality of fuel materials may be stacked axially as shown in FIG. 1B, but this is not necessarily so. For example, the fuel element may comprise only one fuel material. In one embodiment, the spacing (s) 15 may be between the fuel material and the cladding material, but the spacing (s) need not necessarily be present. In one embodiment, the spacing is filled with a compressed atmosphere, e. G., A compressed helium atmosphere.

The fuel may comprise any fissile material. The fissile material may comprise a metal and / or a metal alloy. In one embodiment, the fuel may be a metal fuel. It is understood that metal fuels can provide a relatively high heavy metal load and excellent neutron economy, which is desirable for a breed-and-bum process in nuclear cracking reactions. Depending on the application, the fuel may comprise at least one element selected from U, Th, Am, Np and Pu. The term " element " when referring to chemical symbols herein may refer to an element identified in the periodic table, which should not be confused with the " element " In one embodiment, the fuel may comprise at least about 90 weight percent U, such as at least 95 weight percent, 98 weight percent, 99 weight percent, 99.5 weight percent, 99.9 weight percent, 99.99 weight percent, have. The fuel may further include a refractory material. The refractory material may include at least one element selected from Nb, Mo, Ta, W, Re, Zr, V, Ti, Cr, Ru, Rh, Os, Ir, . ≪ / RTI > In one embodiment, the fuel may comprise additional combustible poisons, such as boron, gadolinium, or indium.

The metal fuel forms an alloy with about 3 wt.% To about 10 wt.% Zirconium to stabilize the alloy in size during irradiation, and can prevent low temperature eutectic damage and corrosion damage of the cladding. The sodium thermal bond fills the gaps that exist between the alloy fuel and the inner wall of the clutting tube to allow fuel swelling and provide efficient heat transfer, thereby keeping the fuel temperature low. In one embodiment, the individual fuel element 11 has a thin wire 12 having a diameter of about 0.8 mm to about 1.6 mm that is helically wrapped around the circumference of the cladding tube so that the fuel assembly 18 and / 20) and provide a coolant space (also acting as a coolant duct). In one embodiment, the cladding 13 and / or the wire wrap 12 may be fabricated from the ferrite-martensitic steel due to its irradiation performance as implied by the empirical data.

Fuel element

The " fuel element " in the fuel assembly of the power generating reaction furnace, for example the element 11 shown in Figs. 1A and 1B, can take the form of a generally cylindrical rod. The fuel element can be part of a power generation reactor, which can be part of a nuclear power plant. Depending on the application, the fuel element may have any suitable dimension in relation to its length and diameter. The fuel element may comprise a cladding layer 13 and fuel 14 disposed inside thereof relative to the cladding layer 13. In the case of a nuclear reactor, the fuel may comprise a nuclear fuel (which may be a nuclear fuel). In one embodiment, the nuclear fuel may be a cyclic nuclear fuel. The fuel element may further comprise a liner disposed between the nuclear fuel 14 and the cladding layer 13. The liner may comprise a plurality of layers.

The fuel may have any geometric shape. In one embodiment, the fuel may have an annular geometric shape. In this embodiment, the fuel in the annular form can cause a desired level of fuel density to be achieved after a certain level of bum-up. Such an annular configuration may also maintain the compressive force between the fuel and the cladding to promote heat transfer. The fuel may be configured to have various characteristics depending on the application. For example, the fuel may have an arbitrary level of density. In one embodiment, it is desirable to have a fuel of high density, such as near uranium of the theoretical density possible (in the case of fuel containing uranium). In another embodiment, having a high porosity (low density) may prevent the formation of additional internal voids during irradiation, thereby reducing the fuel pressure on the structural material, such as cladding, during operation of the nuclear fuel.

The cladding material for the cladding layer 13 may comprise any suitable material depending on the application. In one embodiment, the cladding layer 13 may comprise at least one material selected from metals, metal alloys, and ceramics. In one embodiment, the cladding layer 13 comprises at least one element selected from Nb, Mo, Ta, W, Re, Zr, V, Ti, Cr, Ru, Rh, Os, Ir, Nd, Or a refractory material such as a refractory metal, which may be included. In another embodiment, the cladding material may be selected from a ceramic material, such as silicon carbide or aluminum oxide (alumina).

The metal alloy in the cladding layer 13 may be steel in an exemplary embodiment. The steel may be selected from austenite steel, ferrite-martensitic steel, oxide-dispersed steel, T91 steel, T92 steel, HT9 steel, 316 steel, and 304 steel. The steel may have any type of microstructure. For example, the steel may comprise at least one of a martensite phase, a ferrite phase, and an austenite phase. In one embodiment, substantially all of the steels have at least one phase selected from a martensite phase, a ferrite phase, and an austenite phase. Depending on the application, the microstructure may be configured to have specific phases (or specific phases). The cladding layer 13 may comprise an iron-based composition as described below.

At least a portion of the components of the fuel element may be joined. Such bonding may be physical (e.g., mechanical) or chemical. In one embodiment, the nuclear fuel and cladding are mechanically bonded. In one embodiment, the first and second layers are mechanically bonded.

Iron-based  Composition

DETAILED DESCRIPTION OF THE INVENTION In this application, a composition comprising a metal is presented in one embodiment. The metal may comprise at least one of a metal, a metal alloy, and an intermetallic composition. In one embodiment, the metal comprises iron. In one embodiment, the composition comprises an iron-based composition. In one embodiment, the term " X-based " composition may refer to a composition comprising a substantial amount of element X (e.g., a metal element). Such a substantial amount may be, for example, at least 30%, such as at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99% have. Percentages herein may refer to weight percent or volume percent (atomic%), depending on the context. In one embodiment, the iron-based composition may comprise steel.

The composition described herein may be employed as a component of a nuclear fuel element, such as a cladding material of a nuclear fuel element. However, the metal-containing composition need not be limited to a cladding material, and can be employed in any case where such a composition can be employed. For example, in one embodiment, a composition represented by the chemical formula (Fe) a (Cr) b (M) c is presented wherein a, b, and c are each a number greater than 0, Depending on context, these numbers may represent volume percent as an alternative. In one embodiment, b is from 11 to 12, c is from about 0.25 to about 0.9, and a is the balance. In one embodiment, the composition comprises about 0.005 wt.% To about 0.05 wt.% Nitrogen ("N") such as about 0.01 wt.% To about 0.04 wt.%, About 0.01 wt.% To about 0.03 wt. % To about 0.03% by weight of nitrogen. The element M may represent at least one transition metal element. The element M in this iron-based composition may be any transition metal element identified in the periodic table (for example, an element in groups 3 to 12 of the periodic table). In one embodiment, M represents at least one of Mo, Ni, Mn, W, and V.

In another embodiment, the composition may comprise an iron-based composition comprising a steel composition, or may be the iron-based composition. The composition may be represented by the chemical composition formula (Fe) a (Cr) b (Mo, Ni, Mn, W, V) c wherein a, b and c are each a number greater than 0, Depending on the context, the number may alternatively represent volume percent. In one embodiment, the number b is from 11 to 12, c is from about 0.25 to about 0.9, and a is the remainder. In one embodiment, the composition comprises about 0.01% to about 0.04% N by weight.

The composition may comprise at least one additional element. The additional element may be a non-metallic element. In one embodiment, the non-metallic element may be at least one element selected from Si, S, C, and P. The additional element may be a metal element including Cu, Cr, Mo, Mn, V, W, Ni and the like. In one embodiment, the composition comprises Cr (from about 10 wt% to about 12.5 wt%); C (about 0.17 wt% to about 0.22 wt%); Mo (about 0.80 wt% to about 1.2 wt%); Si (up to about 0.5% by weight); Mn (about 1.0% or less by weight); V (about 0.25 wt% to about 0.35 wt%); W (about 0.40 wt% to about 0.60 wt%); P (about 0.03 wt% or less); S (about 0.3% by weight or less). In another embodiment, the composition further comprises about 0.3% to 0.7% Ni by weight. In another embodiment, the composition comprises Cr (about 11.5 wt%); C (about 0.20 wt%); Mo (about 0.90 wt%); Ni (about 0.55 wt%); Mn (about 0.65 wt%); V (about 0.30 wt%); W (about 0.50 wt%); Si (about 0.20 wt%); N (about 0.02% by weight). Other elements may also be present in any suitable amount. In some cases, certain accidental impurities may also be present.

The composition may comprise an iron-based composition comprising a steel composition comprising a tailor-made microstructure. For example, the composition presented herein may comprise a small amount of delta-ferrite phase. In one embodiment, the composition is at least substantially free of delta ferrite. In another embodiment, the composition has no delta ferrite at all. Instead of the ferrite phase, the composition may comprise a martensitic phase (e.g., tempered martensite). In one embodiment, substantially all of the composition represents a martensite phase. In another embodiment, the entire composition exhibits a completely martensitic phase. As described below, one technique for tailoring the microstructure (e.g., to mitigate the formation of ferrite phases) may be to adjust the nitrogen content within the ranges provided herein. Said mitigation herein may mean mitigation and / or prevention, but does not mean complete removal.

The microstructure comprising the phase may be described in terms of chromium equivalence. In one embodiment, the chromium equivalent (" Cr _eq ") is the sum of the ferrite forming elements shown in the configuration diagram for evaluation of phases of stainless steel, weld metal, and is calculated from various formulas. In some cases, chromium equivalents may be used with nickel equivalents, where the nickel equivalents are the sum of the austenite forming elements. The formula can be any suitable formula, at least depending on the chemical characteristics of the material. In one embodiment, the equation may be expressed in net chrome equivalents (net Cr _eq ) corresponding to the difference between chromium equivalents and nickel equivalents. Net Cr _eq (wt%) = (% Cr) + 6 (% Si) + 4 (% Mo) + 11 (% V) + 5 (% Nb) + 1.5 (% W) + 8 (% Ti) + 12 (% Al) - 4 (% Ni) - 2 (% Co) - 2 (% Mn) - (% Cu) - 40 (% C) - 30 (% N). In one embodiment, the compositions described herein may represent Cr _eq of about 10 or less, such as about 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, or A Cr _eq of less than that can be shown. In one embodiment, Cr _eq may be kept below 9 to mitigate the formation of ferrite. Based on the above equation, the N content can play an important role in the value of Cr _eq and thus play an important role in ferrite formation (or lack of ferrite).

Due to the microstructure at least in part, the compositions described herein can exhibit tailored material properties. For example, the composition may exhibit high thermal stability. The thermal stability of one composition in one embodiment may refer to the ability of a particular phase of the composition to withstand decomposition (or dissociation) from high temperature to another. In one embodiment, the compositions described herein are substantially thermally stable at temperatures of about 500 degrees Celsius or more, and are substantially thermally stable at temperatures of, for example, about 550 degrees Celsius, about 600 degrees Celsius or more .

The compositions presented herein may include additional phase (s) or material (s). For example, where the composition comprises carbon, the carbon element may be present in the form of a carbide. In one embodiment, the composition may comprise a carbide substantially uniformly distributed within the composition. The carbide may have any suitable size depending on the application. In one embodiment, the carbide may exhibit a size of less than about 2 micrometers, for example less than about 1 micrometer, less than 0.5 micrometer, less than 0.2 micrometer, less than 0.1 micrometer, or less .

Iron-based  Method of making / using composition

The iron-based compositions described herein and the fuel elements comprising the compositions can be made by a variety of techniques. The iron-based composition may be any of the compositions described herein. For example, the composition may comprise steel. In another embodiment, a fuel element having a tubular structure made by the method described herein is presented. For example, referring to FIG. 2A, a method of making a composition in one embodiment is shown, wherein the method comprises: preparing a composition comprising iron-based compositions at a first temperature under a first condition in which at least a portion of the iron- (Step 201); Cooling the material to a second temperature at a predetermined cooling rate under a second condition in which at least a portion of the iron-based composition is transformed into a martensite phase (step 202); And heat treating the material to a third temperature under a third condition in which the carbide precipitates (step 203). In one embodiment, step 201 and step 202 may together be referred to as normalization, while step 203 may be referred to as tempering.

The first temperature may be any temperature suitable for the first condition. In one example, the first temperature may be higher than the austenitizing temperature of the composition, i.e., the temperature at which substantially all of the ferrite phase of the iron-based composition is transformed into the austenite phase. The austenitizing temperature varies depending on the chemical characteristics of the material. In one embodiment, the first temperature is about 900 degrees Celsius to about 1200 degrees Celsius, such as about 1000 degrees Celsius to about 1150 degrees Celsius, about 1025 degrees Celsius to about 1100 degrees Celsius, and the like. The first temperature may be greater than 1200C or less than 900C, depending on the material.

Referring to FIG. 2B, the heat treatment process at the first temperature may further include heating the material to a first temperature (step 204). The heat treatment at the first temperature may be done for a time of any suitable length depending on the material involved. The time may be adjusted to be long enough to facilitate the formation of a uniform austenite solid solution. In one embodiment, the heat treatment is performed for at least about 3 minutes, such as at least 4 minutes, 5 minutes, 15 minutes, 20 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, . In addition, longer or shorter times are possible. In one embodiment, the heat treatment at the first temperature may be carried out at a temperature between about 1 minute and about 200 minutes, such as between about 2 minutes and about 150 minutes, between about 3 minutes and about 120 minutes, and between about 5 minutes and about 60 minutes, Time. In one embodiment, during the heat treatment at the first temperature (e.g., at the end of the heat treatment), at least a portion of the iron-based composition is transformed into an austenite phase. In one embodiment, substantially all of the composition is transformed into an austenite phase. In another embodiment, the entire composition is completely transformed into an austenite phase. In one embodiment, the first condition alleviates formation of a delta ferrite phase of the iron-based composition. In another embodiment, the first condition promotes substantially all of the iron-based composition being transformed into an austenite phase.

Referring to FIG. 2C, the heat treatment process (step 201) at the first temperature may further comprise dissolving at least substantially all of the carbide (step 205) (if the carbide is present in the iron-based composition of the material) have.

The second temperature in step 202 may be any temperature suitable for the second condition. In one embodiment, the second temperature is less than or equal to 60 degrees Celsius, such as less than or equal to 50 degrees Celsius, less than or equal to 40 degrees Celsius, less than or equal to 30 degrees Celsius, less than or equal to 20 degrees Celsius, less than or equal to 10 degrees Celsius. In one embodiment, the second temperature is about room temperature (e.g., 20 degrees Celsius). Cooling can be done through any suitable technique. In one embodiment, cooling includes cooling by at least one of air and liquid. In one embodiment, the second condition promotes substantially all of the iron-based composition to be transformed into a martensite phase. For example, the cooling may be done at a suitable rate to allow at least a portion of the iron-based composition to deform into a martensite phase during cooling (e.g., at the end of the treatment). In one embodiment, the rate is fast enough to allow substantially all of the composition to transform into a martensite phase. In another embodiment, the rate is fast enough to allow the entire composition to be completely transformed into a martensite phase. In one embodiment, at the end of cooling, the composition is substantially free of at least one phase selected from a ferrite phase and an austenite phase. In one embodiment, at the end of cooling, the composition contains no at least one phase selected from a ferrite phase and an austenite phase.

The third temperature in step 203 may be any temperature suitable for the third condition. The third temperature may be lower than the austenite formation start temperature at which the austenite starts to be formed, and austenite starts to be formed at a temperature higher than the austenite formation start temperature. In one embodiment, the third temperature may be lower than the first temperature. In one embodiment, the third temperature is at least 500 degrees Celsius, such as at least about 550 degrees Celsius, about 600 degrees Celsius, about 650 degrees Celsius, about 700 degrees Celsius, about 750 degrees Celsius, about 800 degrees Celsius, about 850 degrees Celsius, about 900 degrees Celsius, Or higher. In one embodiment, the third temperature is from about 500 degrees Celsius to about 900 degrees Celsius, such as from about 550 degrees Celsius to about 850 degrees Celsius, from about 600 degrees Celsius to about 800 degrees Celsius, from about 650 degrees Celsius to about 780 degrees Celsius About 700 degrees Celsius to about 750 degrees Celsius. Higher or lower temperatures are also possible. The third temperature may be high enough to precipitate the carbide and confer high thermal stability on the carbide, but may be low enough so that the carbide density is high and the carbide size exhibits a uniform carbide distribution for the void swelling resistance have.

Referring to FIG. 2d, the heat treatment at the third temperature may further include heating the material to a third temperature (step 206). The heat treatment at the third temperature may be performed for a time of any suitable length depending on the material involved. In one embodiment, the heat treatment at the third temperature is carried out for a period of from about 0.1 hour to about 5 hours, such as from about 0.2 hour to about 4 hours, from about 0.5 hour to about 3 hours, from about 1 hour to about 2 hours, Lt; / RTI > Times longer than this or shorter times are also possible. In one embodiment, the third condition may alleviate the formation of the ferrite phase and / or the austenite phase of the iron-based composition. In one embodiment, the composition is substantially free of a ferrite phase and / or an austenite phase. The heat treatment may be done through any suitable technique. In one embodiment, the heat treatment at the third temperature is performed in a vertical furnace.

Additional process (s) may be included. For example, referring to FIG. 2E, the method may further comprise cooling the composition from a third temperature to a fourth temperature (step 207). The fourth temperature may be lower than the third temperature. For example, the fourth temperature may be less than or equal to 60 degrees Celsius, such as less than or equal to 50 degrees Celsius, less than or equal to 40 degrees Celsius, less than or equal to 30 degrees Celsius, less than or equal to 20 degrees Celsius, less than or equal to 10 degrees Celsius. In one embodiment, the fourth temperature is approximately room temperature (e.g., 20 degrees Celsius). Referring to FIG. 2F, the method may further comprise adjusting (step 208) the weight percent of N in the iron-based composition of the material to alleviate the growth of the carbide phase of the iron-based composition.

Referring to Figs. 3A to 3C, the difference in the microstructure of the iron-based composition is shown in the figure. Figure 3a shows the microstructure in a typical steel showing lumps of delta ferrite grains, loss of tempered martensite microstructure, and numerous grains without complex carbide microstructure. Figure 3b shows an improved microstructure, note that there is a more homogeneous carbide microstructure in the tempered martensite grains and still some small delta ferrite grains in the microstructure. Figure 3c shows the results of a steel sample subjected to the process described herein. This figure shows an improved microstructure in which most of the grain regions are substantially delta ferrite free in the presence of high density, finely distributed carbides.

Another embodiment provides an alternative method of making a composition. Referring to FIG. 4a, the alternative method of making a composition includes the steps of (at step 401) passing the material through at least one of cold drawing, cold rolling, and pilgering; (Step 402) heat treating a material comprising the iron-based composition to a first temperature under a first condition in which at least a part of the iron-based composition is transformed into an austenite phase; Cooling the material to a second temperature at a predetermined cooling rate under a second condition in which at least a portion of the iron-based composition is transformed into a martensite phase (Step 403); And heat treating the material to a third temperature under a third condition in which the carbide precipitates (step 404).

In step 401, the material is cold worked, and cold drawing, cold rolling, and back and forth repetition are only some examples of processes that can be done on the material. One consequence of the cold work is that the dimensions of the material can be changed to the desired value. For example, the thickness of the material can be reduced as a result of the cold work. In one embodiment, this reduction in thickness may be, for example, at least 5%, for example at least 10%, 15%, 20%, 25% or more. In one embodiment, the reduction is from about 5% to about 20%, such as from about 8% to about 16%, from about 10% to about 15%, and the like. Larger values or smaller values are also possible.

The dimension (s) of the material can be adjusted through an additional process. In one embodiment, the ingot may undergo a thermal-mechanical process to form a material having the desired final dimension (s). Referring to FIG. 4B, the starting material to be treated may be a billet, ingot, forgings, etc. having a cylindrical shape (step 405). The starting material is then mechanically worked (e. G., Cold worked) by an appropriate tubing process (s) (step 406). When the tube making process involves a cold work, the workpiece is annealed ("intermediate annealed") after a work process at a temperature below the austenite start temperature, i.e. below the strain temperature from the ferrite phase to the austenite phase, (Step 407). In one embodiment, austenite needs to be avoided because austenite transforms into hard martensite upon cooling, thereby offsetting the softening process. Steps 406 and 407 are repeated until the final dimension is achieved. In one embodiment, after the final cold working step (step 408) of providing the tube with the corresponding final dimension, the tube is not annealed again. As described above, the tube may then undergo normalization and tempering.

The method may include additional processes. Referring to FIG. 4C, the method may further include the step of extruding the ingot containing the composition (Step 409). Referring to FIG. 4d, the method may further comprise forming an ingot comprising an iron-based composition prior to the discussed steps, wherein the formation of the ingot is performed by cold cathode induction melting, vacuum induction melting, Melting, and electron-slag remelting (step 410). Referring to Figure 4E, the method may further comprise the step of forming the ingot comprising the iron-based composition and the step of purifying the ingot by removing impurities (e.g., P, S, etc.) prior to the discussed step Step 411). The ingot forming process and the refining process may involve any suitable technique. The temperatures described above may vary depending on the material involved and / or its application.

Fuel elements (and fuel assemblies) comprising such compositions (e.g., as cladding) can be used in a variety of applications. In one embodiment, a method of using a fuel assembly is presented. Referring to FIG. 5a, the method of use includes generating power using a fuel assembly (step 501), wherein the fuel element of the fuel assembly comprises any of the iron-based compositions described herein. Referring to FIG. 5B, the generation of such power may include generating at least one of an electrical power and a thermal power (step 502).

Power generation

As described above, the fuel assembly described herein may be part of a power generating device or an energy generating device, which may be part of a power generating plant. The fuel assembly may be a nuclear fuel assembly. In one embodiment, the fuel assembly may include a fuel as described above, a plurality of fuel elements, and a plurality of fuel ducts. The fuel duct may include a plurality of fuel elements disposed therein.

The fuel assemblies described herein may have a fuel composition of at least about 50 MW / m ² , such as at least about 60 MW / m ² , about 70 MW / m ² , about 80 MW / m ² , about 90 MW / m ² , To generate a peak power density per area of ² or more. In some embodiments, the fuel assembly is capable of receiving radiation damage of at least about 120 DPA (displacement per atom), such as at least about 150 DPA, about 160 DPA, about 180 DPA, about 200 DPA, have.

All of the foregoing US patents, US patent application publications, US patent applications, foreign patents, foreign patent applications, and non-patent publications mentioned and / or mentioned in the Application Data Sheet herein are incorporated herein by reference, , The entire contents of which are incorporated herein by reference. Where more than one of the contained documents and similar materials, including but not limited to defined terms, examples of terms, techniques described, etc., are different or inconsistent with the present application, the present application is in accordance with this application.

Yes

An example of the composition described above was prepared and tested for void swelling performance. Three heat hits, designated heat FD, heat CH, and heat DH of the composition, were prepared to meet the details set forth above. Heat CH and heat DH are the same compositions, only differing in slight changes in the final heat treatment. For a relative comparison between the existing HT9 and the embodiment of the composition described herein, the existing HT9 sample of heat 84425 from the ACO-3 duct used in the Fast Flux Test Facility (FFTF) using the same protocol was used for swelling .

The actual composition of the final plate product of each heat was determined by analysis and is presented in Table 1. The actual composition of the existing samples was also measured and is shown in Table 1 as well.

hit FD  Ready

The 50 kg VIM ingot of the steel of the heat FD was heated at 1200 degrees Celsius for 48 hours to homogenize the casting structure and then forged to approximately 70tx100wx450L (mm). The temperature of the furnace for homogenization was controlled by a PID temperature controller and by using a calibrated thermocouple. The forged plates were immersed at 1200 ° C for 2 hours and hot rolled to approximately 24t × 110w × 1,050L (mm) at 70t × 100w × 450L (mm).

A portion of the hot-rolled steel sheet was annealed at 800 degrees Celsius for one hour to facilitate easy surface machining and machined to approximately 0.3 mm per side to remove any oxide film and removed from the surface plate. The steel sheet was then cold rolled to a thickness of 5.4 mm by a number of steps. During intermediate rolling during cold rolling, the steel sheet was annealed at 800 degrees Celsius for 1 hour to soften the cold worked structure. In addition, the furnace temperature for the intermediate heat treatment is controlled by the PID temperature controller of the furnace and by using a calibrated thermocouple.

After cold rolling, the steel sheet was annealed at 800 degrees Celsius for 1 hour to perform easy sawing and cut into smaller pieces for final heat treatment.

After cutting, a final heat treatment was performed on one of the smaller pieces. This piece, named Heat FD, was heat treated [as part of batches of pieces of other steel] at 1000 degrees Celsius for 30 minutes and then air-cooled to room temperature to obtain the martensite structure. The temperature of the furnace for the normalization heat treatment was controlled by a PID temperature controller and by using a calibrated thermocouple. Moreover, new thermocouples were attached to the spot welds on one of the pieces in the heat treatment batch. The heat treatment batch comprising the piece attached to the thermocouple was put into the furnace at the normalization temperature and a count of the final normalization heat treatment time after the thermocouple attached on the piece reached the normalization temperature count). After holding for the specified time, the heat treatment batch was removed from the heat.

The normalized pieces of Heat HD were heat treated at 750 degrees Celsius for 0.5 hour to temper the martensitic structure and then cooled to room temperature. The temperature of the furnace for the final tempering heat treatment was controlled by a PID temperature controller and by using a calibrated thermocouple. In addition, the heat HD pieces were part of a batch of other steel pieces, including thermocouple-attached pieces as described above. The batch was introduced into the furnace heated to the tempering temperature and the count of the final tempering treatment time was started after the thermocouple attached on the piece reached the tempering temperature or 750 [deg.] C. After holding for 30 minutes, the tempered batch was removed from the furnace.

The Vickers hardness of the tempered heat HD pieces was tested three times, 238, 246, and 241, with an average of 242.

Heat CH and Heat DH's  Ready

Figures 6a and 6b show a process outline of the major process steps used to facilitate plate production and tube production in the heat (CH and DH). The initial process steps (vacuum induction melting (VIM), vacuum arc reflow (VAR), and homogenization) were applied to both heat.

One particular peculiarity of this fabrication process is the application of a second homogenization heat treatment at 1180 degrees Celsius for 48 hours after hot rolling the plate or after the second cold rolling step or the third cold rolling step for the tube.

Swelling test

In order to measure the swelling performance of the composition, the plates of each of the above-described three heat and conventional control samples were subjected to a heavy ion irradiation test. The investigation was done in an ion beam laboratory using dual ion (Fe ⁺⁺ and He ⁺⁺ ) irradiation beams to simulate the formation of He from the (n, a) reaction and the subsequent formation of voids in the neutron environment. At an irradiation dose level of 188 dpa, Fe ⁺⁺ ions and low current He ⁺⁺ ions with an energy of 5 MeV were directed to the steel samples at temperatures of 440 ° C, 460 ° C, and 480 ° C. Approximately 2 MeV of He ⁺⁺ ions were delivered through the Al foil with a thickness of approximately 3 micrometers to deteriorate its energy and to accumulate He ⁺ in the steel to an appropriate depth. The exact He ⁺⁺ beam energy depends on the exact thickness of the Al foil. The Al foil is rotated about the He ⁺⁺ beam to change the angle of incidence of the beam and to change the depth of implantation in the steel in the 300 to 1000 nanometer range. The incident angles vary from 0 to 60 degrees at five different intervals, with different retention times for each incident angle, resulting in cumulative intensities in the range of 300 to 1000 nanometers and a substantially uniform (10%) He concentration Lt; RTI ID = 0.0 > 5 < / RTI >

The investigation was performed on three heat and conventional control samples using a 3MV pellitron accelerator. The normal beam current is a defocused Fe ^{+ +} ion of 5 MeV at approximately 100 to 400 nA on the sample and a He ⁺⁺ beam of approximately 2 MeV focused to a 3 mm diameter as 0.255 kHz in the x direction and 1.055 kHz in the y direction The sample was investigated using a combination of raster-scanned He ⁺⁺ beams. Prior to each irradiation, the gas was removed from the stage to a pressure of less than 1 x 10 < ^-7 > torr. Immediately before the sample, a beam current was recorded every 30 to 60 minutes using a Faraday cup. The beam was irradiated at a depth of 600 nm using a 40 kV displacement energy and a Quick Kinchin-Pease mode, Ions in Matter) The integrated charge (the product of current and time) is transformed into a quantity based on the damage rate result of the calculation.

The samples were mechanically polished using SiC paper to a maximum # 4000 fine grit and subsequently polished to a maximum of 0.25 micrometer with a diamond solution, with 0.02 colloidal silica solution prior to irradiation, Polishing was carried out. After mechanical polishing, the specimens were electronically polished at a temperature of minus 40 degrees Celsius to minus 50 degrees Celsius in 90% methanol and 10% perchloric acid solution for 20 seconds, where a voltage of 35 V was applied between the specimen and the platinum mesh cathode .

Temperature control was achieved using a series of thermocouples used to calibrate a two-dimensional pyrometer at the irradiation temperature after being immersed in a heated irradiated sample. The temperature was adjusted to ± 10 ° C using an image pyrometer throughout the irradiation.

Preparation of the sample to be irradiated was accomplished using a cross-section focused ion beam (FIB) lifted out from the irradiated surface of each sample. This lift-out method allows the entire irradiated area to be imaged and allows the void image analysis to be done consistently only at a desired depth.

Figure 7 illustrates a typical transmission electron microscope (TEM) image illustrating a depth effect on the void produced by irradiation. The void imaging was performed on a JEOL 2100F TEM. As shown in FIG. 7, the void measurement contained only voids that were within the damaged region depth of 300 to 700 nm into the sample only. By performing the analysis in this manner, all voids on the surface (0-300 nm) that are affected by changes in surface effect and surface composition were not considered. In addition, not all voids at the end of the damage curve (greater than 700 nm), which could be affected by self-interstitial implantation of Fe ⁺⁺ ions, were also considered. The self-interstitial ion at the end of the damage curve tends to inhibit void nucleation by affecting the vacancy / interstitial vias that cause void nucleation.

The zero energy loss fraction was measured and the sample thickness was measured using electron energy loss spectroscopy (EELS) to determine the sample thickness. Using the sample thickness and image area, the void density and swelling measurements can be made.

As noted above, the investigation included samples from the ACO-3 duct HT9 material achieved from the FFTF for comparison of relative swell for the composition examples described above. In order to make a relative comparison of the swelling behavior among various heat, the above-mentioned four heat (CH, DH, FD, and ACO-3) were subjected to heavy ion irradiation. The swell response was also compared to the recording of HT9 from the ACO-3 duct wall in the FFTF program (Hit 84425), which was also irradiated at 443 degrees Celsius in an amount of 155 dpa, which is approximately 0.3% Swelling. Information on existing hits of the HT9 in the FFTF program can be found in O. Anderoglu et al., "Phase Stability of an HT-9 Duct Irradiate in FFTF", published in the Journal of Nuclear Materials No. 430, pp. 194-204 Can be found.

In order to quantify the difference in swelling performance between the present example of the composition and conventional ACO-3 steels, E. Getto et al. Published in Journal of Nuclear Materials 480, 159-176, The swelling% data in FIG. 8 was measured using the process identified in Section 2.2 of "Microstructure Evolution At Very High Damage Level In Self-Ion Irradiated Ferritic-Martensitic Steels" . Each time the percent swell is used in this disclosure, this percent swell is calculated by the process identified in Section 2.2 above.

Figure 8 shows the swelling results for various heat. Figure 8 clearly shows the difference in void swelling performance of the composition examples for the recorded ACO-3. At low temperatures and high temperatures, i.e., 440 degrees Celsius and 500 degrees Celsius, swelling was scarcely detected on any heat. However, at a temperature of 460 degrees Celsius and 480 degrees Celsius, each of the three hits for the composition of the present invention exhibited a significant improvement in swelling in comparison to conventional ACO-3 steels.

Figure 9 shows the TEM collage of the void microstructure at 4 heat after irradiation at 480 degrees Celsius to 188 dpa at 0.2 appm He / dpa where the void is presented as a black feature. The ACO-3 sample exhibited a non-uniform distribution of voids, while having large clusters of multiple voids. The hits for the compositions of the present invention each show a clear improvement to ACO-3. The difference between the heat for the composition of the present invention and ACO-3 is surprising and reflects the difference in void culture between the embodiment of the steel composition described herein and ACO-3.

Figure 10 shows the TEM collage of the void microstructure in the four hits after irradiation at 460 degrees Celsius to 0.015 apps He / dpa to 188 dpa. In addition, the hits for the compositions of the present invention each show a distinct improvement over ACO-3.

The example given above is a steel with the following composition:

From about 10.0 wt% to about 13.0 wt% Cr;

From about 0.17% to about 0.23% by weight of C;

About 0.80 wt% to about 1.2 wt% Mo;

Up to about 0.5 weight percent Si;

About 1.0 percent by weight or less of Mn;

About 0.25 wt.% To about 0.35 wt.% V;

From about 0.40% to about 0.60% W;

At least 80% by weight of Fe

, The steel having a surface of 500 to 700 nm below the surface after irradiation of the double beam Fe ⁺⁺ and He ⁺⁺ to an amount of 188 dpa (displacements per atom) at 0.2 appm He / dpa , Less than 0.75%, less than 0.5%, and even less than 0.3% swelling in the depth of less than 0.9 vol.% In the depth of the SRM using the KP option for the damaged cascade and 40 eV displacement energy, Range in Matter), and a raster of approximately 2 MeV of He ⁺⁺ ions delivered through a thin Al foil for scattering and energy reduction to form a uniform He profile at the sample depth. Was generated by irradiating the steel composition at 460 degrees Celsius using a deflected beam of scanned beam and 5 MeV of Fe ⁺⁺ ions.

With regard to the use of substantially any plural representation and / or singular representation herein, one of ordinary skill in the art may understand plural, singular and / or plural singular forms, as appropriate, depending on context and / or usage. The various singular / plural combinations are not explicitly described herein for the sake of clarity.

The subject matter described herein sometimes refers to various compositions that are included in different compositions or are associated with different compositions that are different. It will be appreciated that the architecture shown is by way of example only, and that a number of different architectures can be injected to achieve the same functionality in practice. From a conceptual viewpoint, any configuration of components for achieving the same function is effectively " associated " to achieve the desired functionality. Thus, any two components May be viewed as " associated " with each other to achieve the desired functionality, regardless of the architecture or intervening components. Likewise, any two components so associated may also be seen as " operably coupled " or " operably coupled " to one another to achieve a desired function, Any two components may also be viewed as " operably coupled " to one another to achieve the desired functionality. Specific examples of operably associatable include, but are not limited to, components that may be physically coupled and / or physically interacting components and / or wirelessly interacting components and / And / or < / RTI > logically interacting components and / or logically interacting components.

In some instances, one or more of the components may be referred to herein as "consisting of," "consisting of," "configurable to," "operable to," " , "To do", "to do", "to conform to", and "to conform to". Skilled artisans will appreciate that such terms (e.g., " configured to ") are intended to encompass components in an operational state and / or components in a non-operational state and / You can do it.

While specific embodiments of the subject matter of the present invention described herein have been illustrated and described, modifications and variations can be made without departing from the broader aspects of the subject matter described herein and on the basis of the teachings herein It will be apparent to those skilled in the art that the appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of the subject matter set forth herein. Those skilled in the art will appreciate that the terms used in the generality herein and specifically in the appended claims (e.g., the appended claims) are generally referred to as " broadly interpreted. &Quot; Should be construed as including, but not limited to -, the term " comprising " should be interpreted as " having at least " and the term " comprising " should be interpreted as " , Etc. should be interpreted in this manner). Skilled artisans will appreciate that, where a specific number of the recited claims is intended, such intent is expressly set forth in the claims, and that such disclosure is not intended without such express written description. For example, to facilitate understanding, the following appended claims may include the use of the phrases " at least one " and " one or more " The use of such phrases, however, is not to be construed as an intention to limit any particular claim, including the introduction claim phrase, to a claim comprising only one such claim, Even when the same claim includes the phrase " at least one " or " at least one " and the singular representation (e.g., the singular representation is usually to be interpreted as " The same applies to the use of the expression "above " Additionally, even if a specific number of the claims recited is expressly stated, one of ordinary skill in the art will recognize that such description is normally to be construed to mean, at least, the stated number (e.g., "2 Quot; substrate " means usually at least two corresponding substrates or two or more substrates). Also, where an expression similar to " at least one of A, B, and C, etc. " is used, this structure is generally intended in the sense that those skilled in the art will understand the expression (e.g., " A and B together, A and C together, B and C together, and / or A, B, and C together, C, and the like). In the case where an expression similar to "at least one of A, B, or C" is used, this structure is generally intended in the sense that one of ordinary skill in the art would understand the expression (eg, "A, B, or C A and B together, A and C together, B and C together, and / or A, B, and C together, but not limited thereto. A system including the above, and the like). It will also be appreciated by those skilled in the art that, in the detailed description, the claims, or the conjunction and / or the transcription phrase generally suggesting two or more alternative terms in the drawings, But should be understood as considering the possibility of including both. For example, the phrase "A or B" is generally understood to include the possibilities of "A", "B" or "A and B".

In the context of the appended claims, those skilled in the art will understand that the operations described in the claims may generally be made in any order. It should also be understood that while the various workflows are presented in order, these various workings may be done in different orders not shown or may be done at the same time. An example of such an alternating sequence is a sequence of nested sequences, inserted sequences, interrupted sequences, reordered sequences, augmented sequences, preparative sequences, supplementary sequences, concurrent sequences, reversed sequences, Other variations may be included. In addition, expressions such as " responding to ", " related to ", or adjectives of other past tense are generally not intended to exclude the foregoing variations unless the context clearly indicates otherwise.

Skilled artisans will appreciate that the specific processes and / or devices and / or techniques described above may be implemented with a more general process and / or a technique, as taught elsewhere herein and / or elsewhere in this application, Or devices and / or techniques described herein.

While various aspects and embodiments are disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for the purpose of illustration and are not intended to be limiting, with the true spirit and scope being indicated by the following claims.

Any portion of the process described herein may be automated. Such automation can be accomplished by involving at least one computer. Such automation may be performed by a program stored on at least one non-volatile computer-readable medium. The medium may be, for example, a CD, a DVD, a USB, a hard drive, or the like. Selection and / or configuration of the fuel element structure, including the assembly, may also be optimized by using a computer and / or software program.

The above-described embodiments of the present invention can be implemented in any of various ways. For example, some embodiments may be implemented using hardware, software, or a combination thereof. When any aspect of a given embodiment is at least partially implemented in software, the software code may be executed on a collection of any suitable processor or processors, whether provided in a single computer or distributed to multiple computers.

In addition, the techniques described herein may be implemented as a method, and at least one example of such a method is presented. The tasks performed as part of the method may be sequenced in any suitable manner. Thus, it is possible to construct an embodiment in which tasks are performed in any of a variety of different orders from the point of view of being presented, and this embodiment includes performing some tasks at the same time, even if they are shown as sequential tasks in the presented embodiment .

It should be understood that all definitions as defined and used herein supersede the conventional meaning of dictionary definitions, definitions in the documents included by reference, and / or definitions of terms.

When used in the description and the claims, the singular should be understood to mean " at least one, " unless explicitly stated to the contrary.

It is to be understood that the phrase " and / or " as used herein in the specification and claims is intended to indicate that the connected elements (i. E., In some cases connected elements and in other cases, Quot; one or both ". A number of elements listed with " and / or " should be interpreted in the same manner, i.e., " one or more " There may optionally be elements other than those specifically specified by the " and / or " syntax, whether specifically associated with or unrelated to the specified elements. Thus, as a non-limiting example, " A and / or B " when used in conjunction with an open phrase such as " comprising " means that, in one embodiment, only A (optionally including non- ), In other embodiments only B (optionally including non-A elements), in another embodiment both A and B (optionally including other elements) Quot ;, " other ", or the like.

As used herein in the specification and claims, " or " should be understood to have the same meaning as " and / or " as defined above. For example, in the written description, " or " or " and / or " between articles should be interpreted as being inclusive, i.e., " including at least one, Quot ;, " element ", or " list of elements ", and, optionally, " The phrase "consisting of" when used in either the appended or explicit language, such as "one of only one" or "specifically one of," or the like, refers to a plurality of elements or precisely one element . In general, the term " or, " when used herein, refers to an exclusive term (such as " any one, " " Should be construed as indicating an alternative (i.e., "one or the other but not both"), and when used in the claims, "consisting substantially of" It has meaning.

It should be understood that, as used in the specification and claims, when referring to the listing of one or more elements, the phrase "at least one" should be understood to mean at least one element selected from any one or more elements in the listed elements And does not necessarily include at least one of each of the elements specifically mentioned within the listed elements, and does not exclude any combination of the elements in the listed elements. This definition also allows for the optional presence of elements other than specifically identified elements belonging to the list of elements for which the phrase " at least one " modifies, whether specifically related to or unrelated to the specified elements do. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B" or equivalently "at least one of A and / or B" At least one (and optionally including non-A) elements that optionally include more than one B without at least one (and optionally including non-B elements) optionally containing more than one A without B, , And in alternative embodiments optionally at least one (and optionally including other elements), including at least one containing more than one A and optionally more than one B, and so on.

Any range referred to herein is inclusive. The phrases " substantially " and " about " used throughout the description are intended to explain and contemplate minor variations. For example, such a representation may indicate ± 5% or less, such as ± 2% or less, ± 1% or less, ± 0.5% or less, ± 0.2% or less, ± 0.1% or less, ± 0.05% or less.

In the foregoing specification, as well as in the claims, all connections such as "including," "including," "having," "accommodating," "accompanying," "maintaining," " Should be understood to be open-ended, i.e., to mean "including but not limited to." Only the ports "consisting of" and "consisting substantially of" will each be closed or semi-closed, respectively, as described in Section 2111.03 of the US Patent and Trademark Office Patent Examination Guidelines.

The claims should not be read as being limited to the order or effect described, unless the effect is referred to. It should be understood that various changes in form and details may be made by those skilled in the art without departing from the spirit and scope of the appended claims. All embodiments falling within the spirit and scope of the following claims and equivalents thereto are claimed.

Claims (17)

As the steel composition,
From about 10.0 wt% to about 13.0 wt% Cr;
From about 0.17% to about 0.23% by weight of C;
About 0.80 wt% to about 1.2 wt% Mo;
Up to about 0.5 weight percent Si;
About 1.0 percent by weight or less of Mn;
About 0.25 wt.% To about 0.35 wt.% V;
From about 0.40% to about 0.60% W;
At least 80% by weight of Fe
Wherein the steel composition has a surface area of 500 to 700 nm below the surface after irradiation of the double beam Fe < ⁺⁺ > and He ⁺⁺ to an amount of 188 dpa (displacements per atom) at 0.2 appm He / Is processed to exhibit a swelling of less than 0.9 vol% in depth, as calculated using a damage cascade and a KP option for displacement energy of 40 eV to simulate a Stopping Range in Matter (SRM) , A raster-scanned beam of approximately 2 MeV He ⁺⁺ ions and a 5 MeV Fe ⁺⁺ ion transmitted through a thin Al foil for scattering and energy reduction to form a uniform He profile at the sample's irradiation depth By irradiating the steel composition at 460 degrees Celsius with a defocused beam of the composition. The method of claim 1 wherein the treatment of the steel composition comprises modifying at least a portion of the steel composition into austenite phase by heating the steel composition to a temperature between 1100 degrees Celsius and 1300 degrees Celsius for 40 to 60 hours ≪ / RTI > The steel composition of claim 1, wherein the steel composition exhibits a swelling of less than 0.75% by volume. The steel composition of claim 1, wherein the steel composition exhibits less than 0.5 volume percent swelling. The steel composition of claim 1, wherein the steel composition exhibits less than 0.3% by volume swelling. The steel composition according to claim 1, wherein the steel composition is HT9 steel. A fuel element made of the steel composition of claim 1. A fuel assembly component made from the steel composition of claim 1. As the steel composition,
(Fe) _a (Cr) _b is represented by the (Mo, Ni, Mn, W , V) c N d
here,
a, b, c, and d are numbers greater than 0 representing weight percent,
b is from 11 to 13,
c is from about 0.25 to about 0.9,
d is from about 0.01 to about 0.04,
a represents the remaining amount,
The steel composition had a swelling of less than 0.9% by volume at a depth of 500 to 700 nm beneath the surface after irradiation of the double beam Fe ⁺⁺ and He ⁺⁺ to an amount of 188 dpa (displacements per atom) at 0.2 appm He / dpa Which is calculated as a result of SRC (Stopping Range in Matter) simulation using the damaged cascade and the KP option for displacement energy of 40 eV, and is used to form a uniform He profile at the irradiation depth of the sample Using a raster-scanned beam of approximately 2 MeV of He ⁺⁺ ions and a defocused beam of 5 MeV of Fe ⁺⁺ ions delivered through a thin Al foil for catering and energy reduction, the steel composition was irradiated at 460 degrees Celsius ≪ / RTI > The steel composition of claim 9, wherein b is between 11.5 and 12.5. 10. The method of claim 9, wherein the treatment of the steel composition comprises modifying at least a portion of the steel composition into austenite phase by heating the steel composition to a temperature between 1100 degrees Celsius and 1300 degrees Celsius for 40 to 60 hours ≪ / RTI > The steel composition of claim 9, wherein the steel composition exhibits a swelling of less than 0.75% by volume. The steel composition of claim 9, wherein the steel composition exhibits less than 0.5 volume percent swelling. 10. The steel composition according to claim 9, wherein the steel composition exhibits a swelling of less than 0.3% by volume. 10. The steel composition according to claim 9, wherein the steel composition is HT9 steel. A fuel element made of the steel composition of claim 9. A component of a fuel assembly made of the steel composition of claim 9.

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